Power supplies for ionization type loads such as electrostatic air cleaners have long been made by iron core and wire windings connected to a normal 110 volt 60 cycle voltage source. Such power supplies are not only expensive, but must be tailored to a particular load range.
The present invention is an improvement to a fly-back bifilar primary winding transformer which is powered by a pulsating 25 kilohertz source to provide an output voltage to a load of a wide range such as various sizes of electrostatic air cleaners. The voltage output to the load is controlled by modulating the pulse width of the voltage input to the transformer depending upon the output voltage and current delivered to the load. The power supply has a backup overload sensing circuit for limiting the pulse width should the output current delivered to the load exceed some predetermined value.